Stack top



P 1959 A. M. SCHROEDER 2,903,956

STACK TOP Filed July 28, 1958 ATTORNEYS.

United States Patent STACK TOP Arthur M. Schroeder, Chicago, Ill.

Application July 28, 1958, Serial No. 751,296 2 Claims. (Cl. 98-84) This invention relates to stack tops and more particularly to a top structure for preventing side or downdrafts from interfering with the proper operation of a furnace stack or chimney.

When a stack or chimney is located in a position adjacent to higher structures such, for example, as the chimney of a relatively low building surrounded by buildings as high as or higher than the chimney, winds create very erratic air currents around the chimney including relatively strong downdrafts. Such downdrafts may in many cases be of sufficient velocity not only to destroy the draft effect of the stack or chimney but to cause an actual downfiow of combustion gases therein. This can result in a backflow of combustion gases into the furnace and the area surrounding it, creating a danger of explosions or of dangerous contamination of the atmosphere within the building.

It is one of the objects of the present invention to provide a stack top which will maintain an effective draft in a stack or chimney even when subjected to downdrafts.

Another object is to provide a stack top which is simple to construct, light weight, easy to install on existing stacks or chimneys, and which functions effectively to maintain the draft in the stack or chimney regardless of downdrafts or other erratic air currents around it.

According to a feature of the invention, the top of the stack or chimney is covered with a cap and a sleeve surrounds the cap or chimney or stack top to define a passage for either upward or downward flow of air and combustion gas therethrough. Preferably an additional tubular structure is provided below the sleeve defining vertical passages through which air and gas can flow down around the chimney under the influence of downdrafts.

The above and other objects and features of the invention will be more readily apparent from the following description when read in connection with the accompanying drawings, in which Figure l is a top view of a stack top embodying the invention;

Figure 2 is a side elevation; and

Figure 3 is a vertical section.

The stack top as shown comprises a tubular stack member which may be formed of sheet metal and which is of a size to fit over or into a stack or chimney and to form an extension thereof. A cap 11 also preferably formed of sheet metal is supported above the top of the stack member 10 by means of spaced strips or brackets 12. As shown, the cap 11 is conical in shape with its large diameter end downward and of a slightly greater diameter than the stack member 10 to project slightly beyond the outer surface thereof.

The upper end of the stack member 10 and the cap are surrounded by a vertical sleeve 13 formed of sheet metal and which may be hexagonal in section, as best seen in Figure l. The sleeve 13 is of greater internal diameter than the cap 11 or the stack member 10, so that it is 2,903,956 .R sdse tis, .195

sp d :from both the. can nd hestac lmem erand :is f a v tical least. o projec abqvethe tlowerte g u the cap an jib1QW1jh top .isof :t e sta k member B neath t sl v h staeklmember may shee metal structure which defines a plurality of vertical tubular passages around the stack member. As shown, this structure may be in the form of a vertical sheet of metal bent to define a series of adjacent channel-shaped elements 14 positioned against the stack member and cooperating with the stack member to define vertical passages around it. Preferably the sheet metal structure defining the channels 14 is cut to define an upward taper at its upper end as indicated at 15 and an undercut 16 at its lower end. With this construction the lower edges of the channel elements 14 may rest on the top wall of a chimney or the like with the stack member 10 extending into the chimney to leave open passages between the chimney top and the lower ends of the tubular passages defined by the channel elements 14.

With the stack top as shown positioned on a stack or chimney, it will protect the stack or chimney against interference with the natural draft thereof by all types of erratic air currents, including direct downdrafts. When the air around the stack or chimney is relatively static the combustion gases rising through the stack or chimney will pass upward through the stack member 10, between the lower edge of the cap and the top of the stack member and upward between the cap and the sleeve 13. The sleeve 13 will protect the top of the stack member against side drafts so that they cannot interfere with proper operation of the stack. When a downdraft occurs the air will flow downward between the sleeve 13 and the edge of the cap and will continue downward through the passages defined by the channel elements 14. The sleeve 13 in cooperation with the cap 11 creates an effect similar to a venturi effect so that combustion gases rising through the stack member 10 will be drawn into the downwardly flowing air stream and will flow downward with the air through the vertical passages 14 and out the lower ends thereof. In this way the desired draft effect of the stack or chimney is maintained under all types of atmospheric conditions so that the furnace with which it is connected will function properly at all times.

While one embodiment of the invention has been shown and described in detail it Will be understood that this is illustrative only and is not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

l. A stack top to prevent interference by downdrafts comprising a tubular vertical stack member, a cap spaced above the top of the stack member, a sleeve open at its top and bottom around and spaced from the top of the stack and the cap, the cap being at least as large in diameter as the stack member but smaller than the sleeve, the lower edge of the sleeve lying below the top of the stack member and the upper edge of the sleeve lying above the periphery of the cap, and channel section strips around the stack member beneath the sleeve defining downwardly extending passages communicating with the sleeve, and extending radially outward beyond a vertical projection of the cap and substantially to the full diameter of the sleeve to receive air currents flowing downward through the sleeve.

2. A stack top to prevent interference from downdrafts comprising a tubular vertical stack member, a conical cap spaced above the top of the stack member and of larger diameter than the stack member, channel beyond the cap and defining a series of vertical tubes terminating at their upper ends below the top of the stack member, and a sleeve mounted above said tubes surroundingand spaced-from the stack member and the cap andof substantially the same radial dimensions as the channel section strips to direct downdrafts around the cap downwardly into-the tuba;

UNITED STATES PATENTS Rowland Feb. 16, 1943 Hogan Nov. 9, 1915 Redgate Oct. 5, 1920 Vallas Mar. 16, 1926 

